Jim, I'm with you, I am regularly amazed at how little TLC some guns get! Yes, a little de-crudding can go a lang way towards keeping a mechanism running well. We like to say how well the 1911 works in "adverse conditions" but that's no reason to leave it carrying around its own coating of same.
Dave, the S&W extractor is the "other" approach, pivoting on a pressed-in pin, as opposed to the Kimber, which pivots upon itself like most shotguns extractors I've seen. I like this setup better but I'm thinking the execution is flawed in the Kimber case. I just got through working on this one that's in the shop, and the symptoms were very much like those you'd see with weak ammo or too much recoil spring-- empty cases getting caught in the ejection port. Also, an occasional empty case was left of top of the empty mag when the last round was fired-- which directs me to the extractor. Extractor tension was fine though, and this is factory hardball and a 16 pound spring. What I found was that the ramp-in of the extractor goes up too high (IMO), so that when the barrel links down, bringing the case with it, the case is barely held or not held by it.
I doubt this is an unusual condition, since the extractor is a MIM part and so, I would say, is going to be utterly consistent, part to part. In other words, I would not expect there to be a few bad ones, where the ramp is dimensionally different from the others. But, no idea how many cavities there are in the mold that makes these, there could be some cavities that make good ones and some that make bad ones, so that's a variable, as is the location of the extractor slot in the slide. But I'll bet a velvet Elvis that much of the gnashing of teeth being heard about Kimber functioning problems stems from this.
Lightly scribing a line on the breechface of the Kimber where the ramp-in stops, and on a Colt with a new aftermarket internal extractor in place, I find that the Colt will still hold the case for about .040 after the barrel has linked down. That's a great margin and .040 more than the Kimber, which is right on the edge.
So, what to do? I milled the Kimber extractor in four places. What I'll call the crowding surface, the surface that bears on the cartridge rim and crowds it to the left, I removed .017 here, which in effect moved the ramp/crowding surface junction down about .030. I removed .017 from what in the inspection business would be called the net surface, the surface that contacts the slide and stops the inward pivoting of the extractor. This lets the extractor in more, so that the .017 off the crowding surface does not reduct extractor tension. And, I removed .017 from the inner end of the hook, so that it would be the same height as before. The fourth surface, the angled front of the claw, actually I did not mill it, I just snagged it off on the grinder until it looked about right. Extractor tension was unchanged by all this due to the nice long spring (another reason I prefer this approach) and the fact that .017 >in< translates to less than .017 movment at the back of the extractor, due to the leverage.
For all I know Kimber got onto this long ago and has corrected the part; but I understand this gun to be about a year old.
Of course, I could be all wet here as I won't be test firing until tomorrow, but I'm confident that it's going to work now. It's a pretty easy fix but oh-so-much-easier to have it come right from the factory.
As I've said before I do prefer this style of external extractor (if you must have and external one), but still it is a pain to maintain. The little pusher that acts on the extractor to make it pivot can be put in wrong, and getting the spring retainer in, along with the firing pin stop, is almost a three-handed affair.
The owner asked if I could convert it to use an internal extractor, I said yes but it's impractical I feel, since you'd be left with the slot in the side, and, while the counterbore for the cap to hold the spring in appears to be the same diameter and on the same location as the original setup, the smaller hole for the spring and pusher is off center, which would make just drilling it out larger real touchy..... if I were going to do it I'd say EDM it but criminy-- it'd all cost more than a new slide and still have the dang slot looking you in the face.
Will report on the test firing whether it be

or
